PLEASANTON — Sewer plant operators say there are a billion reasons for the public to tour a sewer plant at 1:30 p.m. Jan. 7.

The Dublin San Ramon Services District has turned more than a billion gallons of wastewater into irrigation water in its plant at 7399 Johnson Drive in Pleasanton, by the crossroads of Interstates 580 and 680.

The free tour will show guests how treatment is done of effluent from Dublin, Pleasanton and southern San Ramon. Reservations are required. For details, visit www.dsrsd.com/tour or call 925-875-2282. The 60- to 90-minute tour is open to those 7 or older.